Inkjet Printhead Preliminary Discharge Position Control
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Solution Overview
Problem
Inkjet printing apparatuses face challenges in simultaneously achieving high resolution and high speed printing due to the contradiction between reducing ink droplet size for better landing accuracy and increasing scanning speed for faster printing, which leads to issues like discharge failures and noise, especially when using pigment ink.
Innovation Solution
The implementation of an inkjet printing apparatus with multiple preliminary discharge positions within the carriage's moving area and a control unit that adjusts these positions based on scanning speed, allowing for preliminary discharge at necessary intervals even during high resolution printing, thereby preventing discharge failures and maintaining high definition printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the scanning speed of the printhead is increased to achieve high speed printing, then printing speed is improved, but landing accuracy of ink droplets deteriorates and vibration and noise increase
Solution Approach 1:
The patent applies preliminary action by performing preliminary discharge operations at predetermined positions (home position and/or opposite side of home position) before actual printing begins. This preliminary discharge prevents ink solidification in the nozzles, ensuring that when printing starts, the nozzles are in a ready state capable of delivering ink droplets with high landing accuracy even at high scanning speeds. The preliminary action prepares the system in advance, resolving the contradiction between speed and precision.
2Manufacturing precision
If the size of ink droplets is reduced to achieve high resolution printing, then landing accuracy is improved, but discharge reliability deteriorates due to increased viscosity and solidification of ink
Solution Approach 1:
The patent performs preliminary discharge operations before printing to prevent ink solidification in the nozzles. By discharging ink at predetermined intervals during the carriage's movement to the home position or to the opposite side, the system ensures that ink remains in a liquid state and flowable throughout the printing process. This preliminary action maintains discharge reliability even when using small ink droplets for high resolution printing.
Solution Approach 2:
The patent changes the timing parameter of discharge operations by introducing preliminary discharge at specific predetermined positions (home position and/or opposite side of home position) independent of the actual printing timing. This parameter change ensures that nozzles are primed with liquid ink before printing begins, maintaining reliability while enabling high resolution printing with small droplets.
3Manufacturing precision
If the scanning speed is decreased to improve landing accuracy, then printing resolution is improved, but preliminary discharge intervals become too long causing ink solidification
Solution Approach 1:
The patent performs preliminary discharge operations at predetermined positions (home position and/or opposite side of home position) regardless of the actual printing speed. By anchoring preliminary discharge to specific positional markers rather than time intervals, the system ensures that preliminary discharge occurs frequently enough to prevent ink solidification even when scanning speed is decreased for high resolution printing. This resolves the contradiction by decoupling preliminary discharge timing from printing speed.
Solution Approach 2:
The control unit monitors the carriage's position and speed, and dynamically adjusts the timing of preliminary discharge operations based on actual printing conditions. When scanning speed decreases, the control unit ensures preliminary discharge occurs at appropriate intervals by using feedback from position sensors, preventing ink solidification while maintaining high landing accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables high resolution printing with reduced scanning speed without increasing preliminary discharge intervals, preventing ink viscosity and solidification issues, and minimizing noise, thus satisfying both high speed and high resolution demands.
Implementation Method 1
a piezoelectric scheme of mechanically vibrating or displacing ink (colored ink) by using piezoelectric elements
Implementation Method 2
a thermal scheme using the pressure generated when ink forms bubbles as it is heated
Implementation Method 3
an electrostatic suction scheme implemented by the application of high voltages
Data Source
AI summary
In an inkjet printing apparatus having a plurality of printing modes with different scanning speeds, first and second preliminary discharge performing positions are provided within the moving area of a carriage as positions where preliminary discharge is performed to cause a printhead to discharge ink irrespective of printing, and a combination of positions where preliminary discharge is performed is set from the first and second preliminary discharge performing positions in accordance with the scanning speed in a set printing mode. This makes it possible to execute preliminary discharge at intervals within necessary intervals even if the scanning speed is decreased when high resolution printing is performed.